Some heating, ventilation, and air conditioning (HVAC) systems utilize multi-compressor assemblies, such as tandem assemblies. The compressors of a tandem assembly can be manifolded together allowing them to work simultaneously on the same heating or cooling circuit to deliver pressurized refrigerant to the HVAC system. In some manifold configurations, oil used as a lubricant in the HVAC system is equalized between the compressors of the tandem assembly by an oil equalization system, such as piping between each compressor that maintains an equal oil level in the oil sumps. When both compressors of the tandem assembly are operating, the oil equalization system ensures that oil is transferred between the compressors to prevent starving or overfilling of any one compressor, or other problems.